Insects Weave A Tangled Web

You’re well aware insects exemplify Mother Nature’s authority to balance the environment. Controlling these pests enhances your growers’ efforts to protect and boost crop yields. To help get a handle on 2011 strategies, we’ve gathered the latest findings and recommendations from experts who make managing crop bugs their business.

Insect pressure in 2010 in some ways surprised those who keep an eye on this issue in Midwest corn and soybeans. While certain geographic hot spots experienced very high pressures of the usual pests and some emerging secondary pests, overall, most report 2010 as an amazingly benign year for insect yield damage.

Of course, with rising crop and input prices in the forecast, that’s no reason to let your guard down in the coming season.

Lessons Learned In 2010

“Uncertainty always exists when it comes to insect control, and that was clearly demonstrated in 2010,” says Hub Miller, Dow AgroSciences Insecticides Portfolio Market Leader. “As we prepared for the past growing season, coming out of a milder winter, we expected higher insect populations. Instead, insect pressure proved to be relatively mild.”

Miller thinks the jury is still out on what the Midwest dry fall harvest will mean for 2011 insect pressure. “The early, dry harvest allowed farmers to make land preparation to insure a clean start for the coming growing season,” he says. “With insects, we often have to think about weather conditions on any given day and weekly crop growth stage. We need our eyes wide open during the growing season.”

Among the tools offered by Dow AgroSciences insect control are Lorsban Advanced and Cobalt, which can provide broad-spectrum control of most common insect pests in corn and soybeans.

Academic Perspectives

Taking a look at the North-Central Midwest, Erin Hodgson, University of Iowa assistant professor, Extension entomologist, says there’s so much transgenic corn acreage that insect pressure was low in 2010. “We saw patchy areas with corn borer and corn rootworm trouble, mainly in refuge areas, and it was sparse,” she says.

Hodgson also observed patchy, low-to-moderate soybean aphid populations. “We did see a mix of defoliators last year, caterpillars and a somewhat unusual pest, celery leaftier,” she says. “Some growers saw trouble with cutworms and armyworms very early.”

In terms of weather effects, Hodgson believes heavy, windy rain in June throughout Iowa hindered aphids from surviving their flight from over-wintering buckthorn hosts to soybeans.

“Aphids are not strong fliers and have trouble making it through migration under inclement weather. A combination of wet weather and many days of over 90-degree heat index slowed reproduction,” she believes.

Hodgson’s advice to retailers: “Continue to promote high-yielding seed. With a specific insect problem, you can try to incorporate host plant resistance to pests like soybean aphids. Syngenta and Pioneer offered it in 2010, and Monsanto will offer it in 2011. Overall, be vigilant in scouting to treat target pests and get the best bang for the buck.”

Looking at the South Midwest, Wayne Bailey, University of Missouri associate professor and research entomologist, says 2010 delivered a mixed bag of insect pressure for both corn and soybeans.

Bailey agrees with other industry colleagues — 2010 was a quiet year for corn insect pressure. On soybeans, he says, it’s a different story.

“We certainly saw problems with soybean podworm/corn earworm across northwest and southwest Missouri,” says Bailey. “I scouted at least 30 fields in the northwest area with major outbreaks. In some fields, growers suffered a devastating 100% loss.”

“Some fields revealed early webworm infestations and were treated with an insecticide or a foliar fungicide,” Bailey reports. “I think the webworm spray knocked out some green clover worm, which appears to carry the fungal pathogen that kills late-season soybean podworm.”

It’s a delicate balance between control of damaging pests and elimination of beneficials.

He also saw odd occurrences such as high numbers of Southern corn rootworm beetles. Soybeans needed not only foliar treatment but also treatment for feeding on flowers. “I’ve never before seen feeding on flowers.”

Bailey’s assessment: “We’re using lots of corn transgenics, which work great on target insects, but secondary pests escape and show up in high numbers.”

Other entomologists report migratory pests such as soybean podworm/corn earworm, green clover worm and stinkbug seem to be moving further north.

Corn Observations

With traited corn acres being the norm, the pests growers sought to control were not much different in 2010: Corn earworm, corn rootworm and European corn borer. Many sources report that black cutworm pressure was slightly higher than in the past.

“The pests we seek to control in corn attack from the moment the seed leaves the planter and hits the ground,” says Chism Craig, Monsanto corn product development manager. “Myriad soil pests feed on seed. We always think about corn being attacked by corn borer and corn rootworm.

“However, in 2010 as you looked north of I-70, we saw one of the heaviest corn earworm infestations experienced in several years. These insects are moving further north every year.”

Craig points out that while some management system worries are eliminated with traited corn seed, the quest for higher yields shifts focus and decision-making to other contributing factors such as hybrid and trait selection, the correct seed population, fertility rates, fungicide and insect control.

SmartStax represents the Monsanto premium trait package with comprehensive insect control and the lowest refuge requirement for corn.

When it comes to production of hybrid seed corn, Dan Sherrod, DuPont product development manager, says: “It’s important to preserve every kernel on every ear. We believe Coragen possesses a growing role in hybrid corn seed production, particularly when used at brown silk to provide longer residual protection from late-season, foliar-feeding insects, such as corn earworm.”

DuPont Insecticides Portfolio Manager Lars Swanson adds: “Even when growers make an investment in seed genetics with insect control traits, sporadic outbreaks come with late-season, foliar-feeding insects, such as Japanese beetles and corn rootworm adults. It’s important to observe each field and compliment the genetic technology with an insecticide application as needed.”

“We still saw insect pressure last year, but grubs, wireworms and those pest types didn’t flair like previous years,” observes Craig Abell, Syngenta agronomist, who covers Illinois. “On the flip side, we worked with growers to use Force CS liquid insecticide in-furrow at planting of traited corn hybrids. On average, they realized 10 to 12 bushels per acre yield increase.” Force CS also offers late-season control of corn rootworms, plus secondary pest control of cutworms, wireworms and grubs — all insects which contribute to yield loss.

Soybean Observations

Options ranging from seed treatments to insecticides to new high-yielding varieties, make investing in 2011 soybean yield opportunities more attractive than ever to growers.

“The favorable fall weather and scouting so far indicates soybean aphid populations did grow late season, but dropped as they migrated away from the crop,” says Aaron Robinson, Monsanto soybean development manager. “Reports show a fair amount of population and egg-laying happening as they overwinter on buckthorn.

“Another possible pest to watch in 2011 would be over-wintering bean leaf beetles in some geographies, particularly in no-till. This pest can reduce stand by clipping cotelydons off early and may transmit soybean mosaic virus to reduce yield later in the season,” he says.

Many retailers will sell seed treatments like Acceleron, which provides an insecticide component to control bean leaf beetles. Acceleron seed treatment offers a fungicide-only option with two active ingredients or an option that also includes an insecticide. Either option may be used to treat Genuity Roundup Ready 2 Yield varieties. Of course, many manufacturers will offer a variety of seed treatments, such as INOVATE from Valent.

“Just because a grower didn’t need to spray last year, doesn’t mean it won’t be needed in 2011,” says Vodrazka. “Common thinking about soybean aphids, for instance, is that wet weather last year kept populations down. Still, we saw pockets of heavy infestation.

“Monitoring populations on wild hosts will determine if aphids migrate early season to the soybean crop,” he says. “Advise growers to be ready to spray.”

Leverage 360 and Belt options control soybean aphids, offer other plant health benefits and work well in an integrated pest management system.

Retailer Cody Loyd, Panhandle Cooperative, Scottsbluff, NE, tells growers: “Insect control represents a vital piece of crop health and yield protection. Even if you do everything else right, lack of insect control can negate all the effort and investment put into the crop.”